Parenkym

Parenkym, or parenchyma, is a term used in biology and medicine to describe the functional tissue of an organ, distinct from its stroma or supporting framework. The meaning differs between plant biology and human or animal anatomy, but in both cases it denotes the tissue that carries out the organ’s core activities.

In plants, parenchyma is the most common type of ground tissue. Parenchyma cells are usually alive at maturity, with relatively thin primary cell walls, large central vacuoles, and the capacity to divide. They populate much of the plant body, including leaves, stems, roots, and fruits. Parenchyma performs a range of metabolic functions: photosynthesis in chlorenchyma, storage of starch, oils, and water, and involvement in secretion and wound repair. Specialized forms include chlorenchyma (photosynthetic), aerenchyma (air spaces for buoyancy and gas exchange), and various storage parenchymas. The tissue is often flexible and can dedifferentiate to participate in repair and regrowth.

In animals and humans, parenchyma refers to the functional cells of an organ, as opposed to the stroma, which comprises supporting connective tissue, blood vessels, and other non-functional components. Examples include liver parenchyma, made up of hepatocytes; brain parenchyma, consisting of neurons and glial cells; and lung parenchyma, containing the alveolar and supporting tissue. In pathology, parenchymal tissue denotes the cells responsible for an organ’s primary function, while the stroma provides structure and support.